A serious outburst of unexpected and completely over the top rage. This style of hissy fit was made famous by former No. 1 ranking professional tennis player, John McEnroe, hence the name. To qualify as an episode of McEnrage, it has to happen in public, with witnesses. (That is not to say that Mr McEnroe did not throw his toys out of the pram in private, simply that we do not know if this is the case.) McEnrage can be a classic, all out, red in the face, foaming at the mouth screech fest, or it can be a much less dramatic thing, but with the inclusion of the phrase, "You cannot be SERIOUS!!"

"Why is Jez outside, chain smoking and pacing?"
"Oh my God, you totally missed it! Dude, it was insane. We got to the window and the woman said they were sold out. Instead of getting tickets to the next showing like the rest of us, he just flipped! Started screaming "You cannot be SERIOUS!!" and smacking his hands against that plastic window, swearing and demanding that he be found a seat immediately. That's his spit they're cleaning off the window now!"
"Jesus, proper McEnrage then!"
"Yeah. Fucking Jez, I don't reckon we'll ever be allowed back here now."